With a sharp increase of service traffic of mobile communication, operators and users of mobile communications networks have increasingly high requirements for network coverage and communication data traffic. Many types of base station antennas that are key components of a network emerge, and corresponding new technologies emerge accordingly. A multibeam antenna is one of these antennas.
A coverage area corresponding to a conventional single-beam antenna is only a wide-beam area. All user equipment in the area accesses a network by using a same beam, and a network capacity is limited. A multibeam antenna can simultaneously form multiple beams that are in different directions and are orthogonal to each other, and the different beams can cover different areas, which significantly improves network capacity. A multibeam antenna generally consists of two parts: a beam forming network (BFN) and an antenna array. The beam forming network is a feeding network matrix, having multiple input ports and multiple output ports. Each input port is referred to as a beam port. In a beam forming network, a digital or analog manner is used to establish an amplitude and phase relationship of multiple mappings between a signal of an input port and a signal of an output port. A beam forming network having N output ports is used as an example. When any input port receives a signal from a base station transceiver, the signal is mapped as N signals with particular amplitudes and phases at the N output ports (for example, N signals have a same amplitude, and have a linear relationship in phase), and the N output ports feed an antenna array to form a beam.
A representative beam forming network is a Butler matrix. However, a Butler matrix has a complex structure and is difficult to fabricate.